Increasingly achieving objectivity of meat grading is one of the main priorities of the meat industry. Accurate grading can help the meat industry determine the price of stock more effectively. This facilitates meat producers in increasing their profit margin and meeting the market's increasing demands for high quality meat. One important element in the grading of carcasses is meat yield, which is estimated using carcass weight and fat and lean depth. Meat yield is directly proportional to carcass weight and inversely proportional to carcass fatness. Another important element is meat quality, such as the marbling score and the paleness, softness, exudativeness of meat (PSE). The exudativeness of meat is the water retaining capacity and soluble protein concentrations in the meat.
Currently, on most production lines the fat/lean depth measurement of pork is performed manually by inserting an electronic infrared probe at a specific predetermined point. This point is set by government regulation for Canada and some other parts of North America for testing pork carcasses and is currently located between the third and fourth ribs 7 cm from the split edge on the back of a suspended carcass. The probe is connected, through a flexible cable, to a computer-based data acquisition system that stores the pertinent information on fat/lean depths. The problems with such a grading method are:
It may cause cross contamination among carcasses through invasive probing. PA1 It is only performed at a single point of the carcass; therefore it provides very limited information for meat yield. PA1 Its accuracy and repeatability are subject to human fallibility, inexperience, and fatigue, etc. PA1 It is costly because one grading station requires two experienced grading operators in each shift since each operator generally only works a twenty minute shift. PA1 The grading system is extremely costly to manufacture and install because of its large size and complex structure. PA1 As the system uses multiple invasive probes, it increases the chance of cross contamination among carcasses. PA1 Because the system does not detect ribs and bones in the carcass, probes are prone to hitting bones during insertion. This reduces the life cycle of the probes and causes high operation and maintenance costs. PA1 Since the instruments are manually operated, the instrument is subject to some of the same problems as invasive manual grading, for example the accuracy of defining the probe location and repeatability of the test are subject to human fallibility, inexperience, and fatigue, etc. PA1 Such instruments require contact between the ultrasound transducer's surface and the carcass skin surface since the ultrasonic signal does not effectively pass through air. The contact force needs to be properly maintained, that is the pressure on the carcass should be constant so that there are no variations in the depth of the penetration of the probe in the malleable outer layer. This requirement is difficult to satisfy continuously in manual operations. PA1 The instruments that produce real-time images are very expensive. PA1 The automated meat grading system has a modular robotic structure. It can meet various grading requirements by using different probes to carry out different grading operations. PA1 The control system of the automated meat grading system is designed based on multi-processor, multi-tasking concept to achieve high speed with regard to real-time control and data processing. PA1 The system software associated with the present invention is designed based on the hybrid environment concept. This concept results in efficient and reliable computer architecture using inexpensive off-the-shelf software and hardware components. PA1 The ribs and bones are detected by using ultrasound sensors in through-transmission mode. PA1 The fat and lean depths are measured by using ultrasound sensors in dual-echo mode. PA1 Ultrasound signal processing software to detect ribs, and measure fat and lean depths is designed by using rule-based expert system technology. PA1 The external shape of carcass is detected to locate the probing position and orient the probe by using multiple distance sensors and data fusing technology. PA1 The softness of the meat (one of meat quality measurements) may be measured from measurements of probing force and calculations using impedance control technology. PA1 A sensor for measuring the marbling score may be carried by the automated meat grading system wherein the marbling score of meat is estimated by using dual-echo mode based on the detection of ultrasound speed through the meat. PA1 a) generating and receiving signals directed at the carcass to obtain data wherein the signals are chosen from the group of ultrasonic and laser sensors; PA1 b) determining the location of the ribs in the carcass from the data to determine the identified ribs; PA1 c) determining a predetermined reference point on the carcass; PA1 d) determining a probing location with reference to the predetermined reference point and the identified ribs; and PA1 e) probing the carcass and obtaining a grading measurement at the probing location. PA1 a) defining rules for identification of the ribs based on anatomical parameters of known carcass ribs including at least an ultrasonic signal profile of a rib; PA1 b) comparing the ultrasonic data with the rules; and PA1 c) determining portions of the ultrasonic data that correspond with at least one rib to determine at least one identified rib. PA1 a) generating and receiving ultrasonic signals with an ultrasonic sensor directed at the carcass to obtain ultrasonic skin data in relation to the position of the sensor; PA1 b) moving the ultrasonic sensor and changing the direction of the signal in relation to the carcass; and PA1 c) determining the position of the sensor when it is normal to the skin.
Alternatively, a fully automated pork-grading system could be used. Currently the abattoirs in Denmark use a fully automated pork-grading systems. In this system only the depths of fat and lean are measured. They are measured by inserting simultaneously fifteen probes at different symmetric positions on each carcass. There is no analysis of the location of the ribs or other indicators on the carcass. The plurality of probes are merely inserted in each carcass in the same position relative to the system. The advantage of this system is that it provides a plurality of measurements which in turn are used to provide a more accurate estimate of fat and lean yield of a carcass than the single probe location system. However, the deficiencies of this approach are that:
More recently the use of ultrasound techniques for fat/lean (non-invasive) grading has been extensively studied as a promising means to avoid the problems associated with the use of invasive probes. Hand-held ultrasound instruments that produce real-time images on a small monitor have been developed and may be used for pork grading. However, the problems with such instruments are that:
In addition there has been some work on various components of automated pork grading systems including work that has been conducted in conjunction with the work of the present inventors. Some of this work has been previously published in graduate theses. However, none of these theses show an integrated system. For example, Ming XU, M.A.Sc. Thesis, entitled Automated Non-Invasive Pork Grading System--Experimental Study and Signal Processing, published by the Department of Mechanical and Industrial Engineering, University of Toronto, 1996, describes an ultra-sound based non-invasive method of obtaining pork grading measurements, however, it does not disclose the integrated system as a whole and without the other components disclosed herein the system could not be used in a production line similar to those currently found in an abattoir. Further, the method disclosed in this thesis is based on two assumptions, firstly that the ultrasonic sensors are positioned where there is no ribs and that the sensors are positioned correctly relative to the carcass. There is nothing in the thesis which explains how to determine the location of the ribs or how to position the sensors. Each of these requirements is fully disclosed herein.
The Rafid Pahlawan, M.A.Sc. Thesis, entitled Surface Following and Detection of the Normal to a Surface--Application to Ultrasonic--Based Pork Carcass Grading, published by the Department of Mechanical and Industrial Engineering, University of Toronto, 1996, describes a method of determining the normal to the skin that is quite different from the present invention. This method while effective would be difficult to meet the speed requirements currently found in an abattoir. Accordingly, heretofore there have been no systems that include all of the components disclosed herein which are necessary to provide a fully automated system using either invasive or non-invasive probing to determine the grade of a carcass.
Accordingly, it would be advantageous to provide an automated meat grading system that would determine the location of the ribs and provide a measurement relative to the quality of the meat at any predetermined location or multiple locations on a carcass. It would be advantageous to provide a meat grading system that could be used in a continuous scanning process. It would be advantageous to provide a meat grading system that can invasively probe meat with a predetermined speed of entry and exit. Further, it would be advantageous to provide an automated meat grading system that is modular. Preferably the automated meat grading system would reduce the likelihood of cross contamination and be more reliable.